Generally, a rolling bearing such as a cylindrical roller bearing includes: an outer ring; an inner ring concentrically arranged inside the outer ring in a radial direction; a plurality of rolling elements arranged between the outer ring and the inner ring so as to roll; and a cage for holding circumferential intervals of the plurality of rolling elements. Further, as a guide system of the cage of the rolling bearing, three guide systems are known, which include an outer ring guide, an inner ring guide and a rolling element guide.
In the rolling element guide of the above-described guide systems, a heat generation or seizure is likely to occur in a pocket of the cage due to: a runout of the cage caused by a centrifugal force generated during a high speed rotation; an increase in a surface pressure by a load received from the rolling elements and a shortage of lubrication on a slide surface. Thus, the rolling element guide is disadvantageous in view of durability. As compared therewith, since the outer ring guide or the inner ring guide (hereinafter refer to as a bearing ring guide) has a higher abrasion resistance performance during the high speed rotation than the rolling element guide, the bearing ring guide can be preferably used, for example, for supporting a main spindle of a machine tool. However, even in the bearing ring guide, the abrasion resistance performance is desired to be more improved. Here, in order to more reduce an abrasion due to a contact of the cage and a bearing ring, lubrication between both the members is requested to be properly maintained. Especially, it is effective to suppress the abrasion in a position where the abrasion is likely to occur.
Further, a radial position of the cage is requested to be stabilized so that the cage is not inclined.
A below-described Patent Document 1 discloses that lubricating oil is supplied to a part between a cage and an outer ring so as to prevent an abrasion or seizure due to a contact of both the members.
Further, the below-described Patent Document 1 discloses that compressed air is discharged from supply holes formed in the outer ring at both sides of a rolling element in the axial direction and the lubricating oil fed by the compressed air is supplied to the part between the cage and the outer ring to prevent the abrasion or seizure due to the contact of both the members. In this technique, the compressed air is sprayed to both the sides of the cage in the axial direction so that the cage may be hardly inclined, however, a rolling bearing of a type is not particularly considered that only one side of a cage in the axial direction is guided by a bearing ring.